I have a board I'm rebuilding and it has some leaking footstrap inserts. I've developed a technique to repair them that I'm sharing in this posting. I test the footstrap insert for air leaks by putting my mouth on it and trying to suck air. On this board, I had two leaking footstrap inserts.

First, the footstrap insert. This pic is of a typical Chinook footstrap insert that I encounter. The insert is one inch tall and the gold tape shows how deep the drilled screw hole extends.

Typically what happens, someone is mounting a footstrap and they don't have the proper length SS screw, so they grab a 1-1/2" long screw and give it a try. When the screw is almost tight enough, the installer experiences a tightness or resistant in the screw. Not knowing the screw has bottomed out in the insert. They give it an extra twist and POP, the screw pops out the bottom of the screw insert hole, creating an instant leak which can ruin a board. The other possibility is they use the right "length" screw but tighten it too tight stripping out the plastic which supports the threads. Either way, this will fix it. It starts with getting some brass threaded inserts such as these which I purchased from Lowes Building Supply. I chose the 10-24 inserts which were about $1.50 for a pack of two, then I purchased 3/4" long 10-24 SS screws to fit them.

To install these in the damaged footstrap insert, I use a drill bit 1/32" larger in diameter that the insert barrel. In this case the "barrel" of the brass insert is 1/4" so I used a 9/32" drill with a depth stop collar set to drill no deeper than the length of the insert.

I drill at very slow speed because the drill has a tendancy to want to drill fast and deep and maybe defeat the "stop collar".

Once the hole is drilled, I mix up some JB Weld to seal the bottom of the hole and to lock the brass insert in place:
I use a toothpick to place a glob of the JB Weld in the very bottom of the hole I just drilled and around the side of the hole. Then I prepare to install the insert. I've found that if you try to drive the insert straight away with a flat blade screw driver, you bust out the side of the recess for the screwdriver, so I install a 1/2" 10-24 screw in the brass insert and use that to install the brass insert.

This pic us just to show how it installs:
Be sure to coat the threads of the insert with JB Weld so they lock in place when the JB Weld sets up.

The actual installed insert on this particular hole stood a bit proud of the board surface:

So, I filed it flush with the surface:

Once filed flush, I installed a 3/4" SS 10-24 screw to clean the threads. I removed the screw and set the board aside for the JB Weld to cure.

That's brilliant! my only concern is the leak at the bottom being properly stopped up.
Might I suggest drilling out the footstrap insert so a clear hole is penetrated into he foam then using a syringe with a very large needle injecting epoxy or JB weld so as to make a solid plug of material at the bottom of the hole.

The material the footstrap insert is made of bonds very well with epoxy like JB Weld. By drilling only the depth of the brass insert, the bottom of the new larger hole is funnel shaped making a good receptical for the JB Weld to bond. When the brass insert is twisted in, it compacts the JB Weld in the bottom of the hole, making a strong and durable waterproof plug. Besides the JB Weld, I've also used "Seamer Mate" a very very high quality sealant with a tenacious bond. I've used Seamer Mate to seal some seams on my Airstream travel trailer and it's one of the best bonding and strongest sealants I've ever seen. I get the small tube of Seamer Mate at Home Depot back in the gutter and downspout area for about $6. The JB Weld or Seamer Mate at the bottom of the new hole only needs to resist less than 5 lbs per square inch of hydrolic pressure to be watertight.

As always thombiz, your pictorial guides to repair and board building jobs are excellent. They are always thorough and very well done. However, I do have a question. Do you find that machine screws hold as well as sheetmetal screws after being tightened down? Also, do you recommend using lock washers of some kind to curb any tendency for loosening?

I've never had a problem with the machine screws loosening up but then I've always used the two screw inserts with machine threads from Chinook when building boards. For those with single screws, the twisting tendancy of the footstrap might cause it to loosen, but the problem would be obvious to the sailor, prompting a tightening of the screw. I don't think a lock washer would help in this situation.

Machine screws only into female brass threads like the Chinook 2 hole inserts should theoretically be stronger than the big wood screw type threaded straight into plastic which can pull straight out and strip the plastic, that's why SB went to the 7M X 32MM, has anyone ever seen the brass insert pulled out of the Chinook inserts? I would think the whole insert would pull out of the board first.
This repair should be just as strong as the original setup, theoretically.

I hope you haven't already done that to your board. Those inserts are for full-depth wood, not stryrofoam laminated with a very thin layer of wood or for the narrow blocks used in most production boards.

Last edited by isobars on Sun Feb 01, 2015 1:34 pm; edited 1 time in total

I would like to add threaded inserts to one of my boards so I can easily switch between single and double foot straps. My board is a 2012 RRD. Does anyone have any information on the dimensions of RRD's inserts? Mainly wondering if the wall thickness is similar to the Chinook. I am thinking someone has repaired one and may have a picture. Or perhaps a destroyed board that could be further dissected.

Not sure if the inserts are similar on most of Cobra made boards but any information would be appreciated.

I am considering using McMaster inserts either part number 99362A600 or 99362A500. These are designed for use in plastic. They are smaller in diameter than the wood type. Also because my inserts are not leaking I may install them without epoxy. The two above inserts are for 1/4 and 10-32 sizes. I have not been able to find them in a metric version but one of these versions would work fine for me.

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